The present invention relates to a trap for insects which are attracted by light.
Insects are a nuisance, and in many cases a health hazard. Various means are employed to kill them. A common method is to use ultraviolet light to attract insects to a high voltage electrocution grid, or to an adhesive trapping board. Electrocution grids and their associated electrical components involve a high capital cost, while adhesive boards have a limited effective life, are expensive and need to be replaced frequently.
The aim of the invention is to provide a trap for insects which is economic to produce and maintain, and which does not suffer from the disadvantages of known traps.
The present invention provides an insect trap comprising an outer casing, an inner casing and a source of electromagnetic radiation, the outer casing having an opening, the inner casing being mounted within the outer casing and having a back wall and a cover, the cover tapering from a first cross-section which matches hat of the opening of the outer casing to a second cross-section which defines an insect entry port leading into a chamber defined, at least partially, by the internal surfaces of the back wall and the cover, at least the back wall and the cover being made of a material that is substantially transparent to electromagnetic radiation having the frequency of the source, and the source being positioned within the outer casing outside the chamber so as to be visible from the open end of the outer casing through the cover.
In a preferred embodiment, the inner casing further comprises side wall means connected to the cover at its first cross-section and to the back wall, the chamber being defined by the internal surfaces of the back wall, the cover and the side wall means. In this case, the outer casing may have a closed end opposite to its opening, and the inner casing may have a cross-section which complements that of the outer casing in such a manner that the inner casing is a close fit within the outer casing at least at the opening of the outer casing, the cover tapering towards the back wall of the inner casing, and the back wall of the inner casing being positioned adjacent to the closed end of the outer casing. Advantageously, the source is positioned between the back wall and the closed end of the outer casing.
Preferably, the cover is integrally formed with the back wall and the side wall means.
The source may be a light source, preferably an ultraviolet light source.
The outer casing conveniently has a generally square cross-section, and the cover takes the form of a square-based pyramid. In this case, the entry port is substantially square.
Alternatively, the outer casing has a substantially rectangular cross-section, and the cover is frustoconical, or the outer casing has an irregular shape, and the cover is frustoconical. In any of these cases, the entry port may be substantially rectangular, circular or elliptical.
In another alternative, the entry port may take the form of an elongate opening defined by angled portions of the cover and the internal side wall means.
Advantageously, the outer casing is made of a material that is substantially opaque to electromagnetic radiation having the frequency of the source, and the cover and the base of the inner casing are made of a plastics material (preferably an acrylic plastics material) transparent to electromagnetic radiation having the frequency of the source.
In another arrangement, the outer casing is generally cylindrical in configuration, having an annular opening in its cylindrical side wall, the annular opening defining the opening of the outer casing, the inner casing having a tubular compartment, an annular top wall and an annular bottom wall, and the cover being constituted by a pair of frustoconical cover plates which converge towards one another to define an annular entry port which surrounds the tubular compartment, and wherein the source is positioned within the tubular compartment.
In this case, the trap may be of modular construction, having a plurality of trap portions. Preferably, the trap has four portions, each having the cross-section of a quadrant of a circle.
In a preferred embodiment, the insect trap further comprises means for deterring insects from leaving the chamber via the entry port, the deterrent means being positioned within the inner casing adjacent to the entry port. Preferably, the deterrent means is constituted by a plurality of substantially parallel electrodes, adjacent electrodes being of opposite polarity, and the electrodes being spaced apart in such a manner that insects of species commonly regarded as pests can simultaneously touch at least two electrodes of opposite polarity.
Advantageously, the electrodes are spaced apart by a distance lying within the range of from 0.5 mm to 2.5 mm, and preferably the electrode spacing is substantially 1 mm. Also, the width of each of the electrodes may lie within the range of from 0.5 mm to 2.5 mm, and preferably the width of each electrode is substantially 1 mm.
Conveniently, the electrodes are provided with means for connection to an alternating current mains supply.
The trap may further comprise current limiting means for limiting the current supplied to the electrodes. Preferably, the current limiting means is such that insects that contact the deterrent means are stunned or disoriented.